OKHttp java.lang.IllegalArgumentException: Unexpec

在使用 okhttp 的時候，head 的一些項是中文，導致網絡請求失敗，錯誤類似下面的

java.lang.IllegalArgumentException: Unexpected char ...

找了一圈發現是 okhttp 對 head 的編碼做了驗證

Header values are (technically) required to be ISO-8859-1 but in practice only ASCII really works and OkHttp validates such (the exception has nothing to do with Retrofit). That string is a custom user agent and you'll need to restrict its contents to the ASCII character set when creating it.

具體的代碼 ( 在 okhttp3 庫裏面的 okhttp3.Headers.java ) 如下:

private void checkNameAndValue(String name, String value) {
    if (name == null) throw new NullPointerException("name == null");
    if (name.isEmpty()) throw new IllegalArgumentException("name is empty");
    for (int i = 0, length = name.length(); i < length; i++) {
        char c = name.charAt(i);
        if (c <= '\u001f' || c >= '\u007f') {
            throw new IllegalArgumentException(Util.format(
              "Unexpected char %#04x at %d in header name: %s", (int) c, i, name));
        }
    }
    if (value == null) throw new NullPointerException("value == null");
    for (int i = 0, length = value.length(); i < length; i++) {
        char c = value.charAt(i);
        if (c <= '\u001f' || c >= '\u007f') {
            throw new IllegalArgumentException(Util.format(
              "Unexpected char %#04x at %d in %s value: %s", (int) c, i, name, value));
        }
    }
}

看源碼，解決的方法很簡單，保證所有的 head 都是符合編碼要求。

但是我的情況是，其中的某一些字符不合要求，這部分服務器不關心，而本地卻又不知道具體哪些是不和要求的。我的解決思路很簡單，挑出不合要求的字符，把這些字符單獨轉碼。

private static String encodeHeadInfo( String headInfo ) {
    StringBuffer stringBuffer = new StringBuffer();
    for (int i = 0, length = headInfo.length(); i < length; i++) {
        char c = headInfo.charAt(i);
        if (c <= '\u001f' || c >= '\u007f') {
            stringBuffer.append( String.format ("\\u%04x", (int)c) );
        } else {
            stringBuffer.append(c);
        }
    }
    return stringBuffer.toString();
}

這樣